How do I use nested iterators with Mustache.js or Handlebars.js?

Question

I would like to use handlebars.js or mustache.js to iterate over a list of families, and then iterate over that family's members. Inside of both loops, I want to display properties of both. However, once I get into the second iteration, none of the family variables are visible.

{{#each families}}
  {{#each members}}
    <p>{{ ( here I want a family name property ) }}</p>
    <p>{{ ( here I want a member name property ) }}</p>
  {{/each}}
{{/each}}

Is this possible? I'd greatly appreciate any help!

Answer 1

You can reference the parent loop variable and index with the ../ operator:

{{#each families}}
  {{#each this.members}}
    <p>Current member: {{ this.name }} (this = inner loop iterator)</p>
    <p>Current family: {{ ../this.title }} (../this = parent loop iterator)</p>
    <p>Current member index: {{ @index }}</p>
    <p>Current family index: {{ @../index }}</p>
  {{/each}}
{{/each}}

Answer 2

I was looking for the same issue using mustache and the answers were given for handlebars, and the ones for mustache required extra JS, I know it is old but I'll add my working example just in case somebody else needs it. Cheers!

JSON:

"experience": [
     {
            "company": "Company 1",
            "position": "Graphic Designer",
            "tasks": ["Task 1", "Task 2", "Task 3"]
    },
     {
            "company": "Company 2",
            "position": "Graphic Designer",
            "tasks": ["Task 1", "Task 2", "Task 3", "Task 4", "Task 5"]
    }
]

TEMPLATE:

{{#experience}}
        <h2>{{company}}</h2>
        <div class="position">{{position}}</div>
        <div class="occupazione">Responsabilities</div>
            <ul>
            {{#tasks}}
            <li>{{.}}</li>
            {{/tasks}}
            </ul>
 {{/experience}}

Answer 3

For a dataset like below:

{
  rows: 
    ["1A", "1B"], 
    ["2A", "2B"], 
    ["3A", "3B"]
}

following will work in mustachejs:

<tbody>
    {{#rows}}
    <tr>
        {{#.}}
        <td>{{.}}</td>
        {{/.}}
    </tr>
    {{/rows}}
</tbody>

Answer 4

Sorry I'm a little late in the game here. The accepted answer is great but I wanted to add an answer that I think is also useful, especially if you are iterating over simple row/column arrays.

When you're working with nested handlebar paths, you can use ../ to refer to the parent template context (see here for more information).

So for your example, you could do:

{{#each families}}
  {{#each members}}
    <p>{{../surname}}</p>
    <p>{{given}}</p>
  {{/each}}
{{/each}}

This was especially useful for me because I was making a grid and I wanted to give each square a class name corresponding to its row and column position. So if rows and columns, simply return arrays, I can do this:

<tbody>
  {{#each rows}}                                                           
    <tr>
      {{#each columns}}
        <td class="{{this}}{{../this}}"></td>
      {{/each}}
    </tr>
  {{/each}}
</tbody>

Update

This solution is for Handlebars. A comment below explains why it will not work in Mustache.

Answer 5

Great answer @maxbeatty.

I just wanted to add another example if anyone have the same problem and can't understand the above solution.

First I have one dimensional array which I wanted to split on every 4 elements:

// this is the one dimensional data we have from let's say a mysql query
var array = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', ...];

// think of it as [[], [], [], [], [], ...]
// but instead we'll be adding a dummy object with a dummyKey
// since we need a key to iterate on
var jagged = [];

var size = 4, // this is the size of each block
    total = array.length / block; // total count of all blocks
// slice the initial one dimensional array into blocks of 4 elements each
for (var i=0; i < total; i++) {
    jagged.push({dummyKey: array.slice(i*size, (i+1)*size)});
}

Now if we pass jagged into our view we can iterate it like that:

<ul>
{{#jagged}}
    <li>
        <ul>
            {{#dummyKey}}
            <li>{{.}}</li>
            {{/dummyKey}}
        </ul>
    </li>
{{/jagged}}
</ul>

If we have our initial array filled with objects:

var array = [{key1: 'a', 
              key2: 'b'},
             {key1: 'c', 
              key2: 'd'},
             {key1: 'e', 
              key2: 'f'},
              ...
];

Then in our template we'll have:

<ul>
{{#jagged}}
    <li>
        <ul>
            {{#dummyKey}}
            <li>{{key1}} - {{key2}}</li>
            {{/dummyKey}}
        </ul>
    </li>
{{/jagged}}
</ul>

Answer 6

You can nest sections easily with lists of objects. Use a data structure where families is a list that has an object members that has a list of any objects (or even more lists)like:

{
  "families" : [
        {
          "surname": "Jones",
          "members": [
            {"given": "Jim"},
            {"given": "John"},
            {"given": "Jill"}
          ]
        },
        {
          "surname": "Smith",
          "members": [
            {"given": "Steve"},
            {"given": "Sally"}
          ]
        }
      ]
}

You would be able to populate a template like:

<ul>
    {{#families}}
    <li>{{surname}}
      <ul>
        {{#members}}
        <li>{{given}}</li>
        {{/members}}
      </ul>
    </li>
    {{/families}}
  </ul>

jsFiddle is currently down so here's the full working HTML with JS:

<!DOCTYPE html>
<head>

  <script src="http://cdnjs.cloudflare.com/ajax/libs/mustache.js/0.3.0/mustache.min.js"></script>
  <script src="http://cdnjs.cloudflare.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
  <script>
    $(function() {
      var tpl = $('#fam').html(),
        data = {
          "families" : [
            {
              "surname": "Jones",
              "members": [
                {"given": "Jim"},
                {"given": "John"},
                {"given": "Jill"}
              ]
            },
            {
              "surname": "Smith",
              "members": [
                {"given": "Steve"},
                {"given": "Sally"}
              ]
            }
          ]
        },
        html = Mustache.to_html(tpl, data);

        $("#main").append(html);

    });
  </script>

</head>

<div id="main"></div>

<script type="template/text" id="fam">
  <ul>
    {{#families}}
    <li>{{surname}}
      <ul>
        {{#members}}
        <li>{{given}}</li>
        {{/members}}
      </ul>
    </li>
    {{/families}}
  </ul>
</script>